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Am I Passing a Kidney Stone? Warning Signs, Risk Factors and Prevention

Kidney stones can strike unexpectedly. Here’s what typically causes stones, what passing them feels like and what you can do.

Kidney stones are small deposits of chemicals and minerals – usually calcium-based – that collect in the kidney before passing through the ureter, bladder and finally out of the body. But while most stones are generally smaller than the size of a peppercorn, says urologist Scott G. Hubosky, MD, they’re well-known for packing a “huge punch.”

Some people carry stones for months, even years, without knowing it, explains Dr. Hubosky. If a stone isn’t traveling through the ureter, it’s often not likely to cause symptoms. This is why the often sudden, severe pain – in the lower back, under the ribs – that may be caused by stones is startling.

Am I at risk for kidney stones?

Anyone can develop kidney stones, regardless of age, though they are more common after age 30. It’s mostly behavioral, as two of the biggest culprits that increase risk are dehydration and excess salt intake, explains Dr. Hubosky. “Salt makes the kidney leak and accumulate calcium. The recommended daily amount of sodium is under 2,500 milligrams (just over one teaspoon of table salt); but most people in our society, by default, consume much more than that when they eat out, grab the saltshaker, and use high-sodium condiments.”

While hydrating and limiting sodium is always wise for your overall health, says Dr. Hubosky, other factors may predispose you, including too much or too little exercise; certain medications; or health conditions, such as diabetes, obesity, metabolic syndrome and inflammatory bowel disease.

What does passing a kidney stone feel like?

It feels different for everyone, says Dr. Hubosky. “Some really big stones may not cause any pain, while other tiny stones may cause a lot of pain.”

Kidney stone pain is also known as renal colic. Because it takes a while for a stone to pass through the entire ureter, pain typically comes and goes in waves. Nausea and blood in the urine may also be experienced.

“Once a stone has reached your bladder, you’ve made it through the worst part,” says Dr. Hubosky. “Until you pass it, you may feel pinching or stinging when you urinate, or a feeling of not being able to empty your bladder fully.”

What does a kidney stone look like?

Kidney stones are typically a little smaller or bigger than the size of a peppercorn and vary in color: black, brown, yellow, gray, and rarely orange or pink.

If you think you may have passed one, you should let your primary care provider and/or urologist know in case there are more to follow, suggests Dr. Hubosky.

Do most kidney stones pass on their own?

It depends on the size and location of the stone. While most stones will pass without complications, this isn’t a guarantee, especially when you’re in severe pain, says Dr. Hubosky. “Don’t hesitate to seek medical care. Many patients go to the emergency room before they see a urologist.”

A small to average-sized stone is 5 millimeters (mm) or less, which passes around 85% of the time. When stones are larger than 5 mm, they’re considered large and more likely to cause complications, such as blockages; in rare cases, stones can grow larger than 10 mm.

Imaging is needed to determine a measurement and whether or not it will pass, notes Dr. Hubosky. If you have a larger stone, the next step is to break it into smaller pieces. You may be a candidate for one of the following procedures:

  • Ureteroscopy with laser lithotripsy: Depending on how far along the stone is, a cystoscope may be used to see inside the urethra and bladder, and a ureteroscope can reach through the ureter, all the way to the kidney, if needed. Lithotripsy breaks up stones with energy, and with ureteroscopy, this is most commonly done with a laser.
  • Extracorporeal shock-wave lithotripsy (ESWL): ESWL is non-invasive and sends high-energy acoustic waves directly to the kidney stone(s) that aims to create smaller stone pieces which can pass. Not everyone is a candidate for this procedure, but a urologist can help determine this.
  • Ureteral stent: A stent may be placed in the ureter to alleviate any obstruction. Stents may be required prior to or after treatment with lithotripsy.

These procedures are usually done once stones have started to move, explains Dr. Hubosky. “Treatment before that is considered elective, but may be highly recommended. Keep in mind, some people have stones that simply need monitoring through a ‘watchful waiting’ approach.”

How can you lower your risk or prevent future kidney stones?

Pay attention to your water, sodium and calcium intake, suggests Dr. Hubosky. Not only is this helpful for your kidneys, but your overall health.

“We often look for a magic number of ounces that we should drink to keep us healthy, but it’s not that simple. Everyone expels water differently; people who work out heavily are going to lose more through sweat, thus they’d need to hydrate more.”

A urologist’s rule of thumb for hydration is to drink enough to produce and expel about two-two and a half liters of urine per day. If you have a urological condition, such as a stone, you may want to measure your urine for a while to make sure you’re drinking enough.

As most stones are calcium-based, you should also maintain an average calcium intake; if your calcium levels are high, your doctor might recommend medication or supplement changes.

“Oxalate” is another “buzzword” when it comes to stones, adds Dr. Hubosky. “An oxalate is a compound that binds with calcium and forms a stone. A lot of sources online talk about ways to lower oxalates, but this isn’t necessary for everyone. Oxalate-rich foods are traditionally healthy – dark, leafy greens; tofu; nut butters – and you don’t want to jump to conclusions and cut them out completely before talking with your doctor.”

Can you “flush” or rush out stones?

While there are countless suggestions online of ways to pass stones quickly, some are not scientifically proven, while others have mixed results in clinical studies, says Dr. Hubosky. The best thing you can do is follow the advice above. Depending on each individual and their stone characteristics, prescription medicine may be helpful.

Stones typically take around two weeks to pass once they’ve left the kidney, although this can vary. The common recommendation that the more water you drink, the quicker they will pass shouldn’t be taken literally, urges Dr. Hubosky. “Hydrating an appropriate amount may help you to pass a stone easier than if you were dehydrated, but it’s also possible to hydrate too much.”

Older adults with cardiac issues, particularly congestive heart failure, should be cautious of how much they drink, since they are more likely to retain fluid.

Additionally, even though it’s rare, overhydrating can also lead to hyponatremia: a condition in which sodium levels in the blood become dangerously low.

The bottom line: kidney stones may develop for a number of reasons, and they affect everyone differently, says Dr. Hubosky. If you notice you may have passed one, or believe you currently are, we’re here to help.

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